A new non-fullerene acceptor based on the combination of a heptacyclic benzothiadiazole unit and a thiophene-fused end group achieving over 13% efficiency. Issue 48 (29th November 2019) - Zhang, Yunqiang
Abstract : A new non-fullerene acceptor based on dithienothiophen[3, 2- b ]-pyrrolobenzothiadiazole and 2-(6-oxo-5, 6-dihydro-4 H -cyclopenta[ c ]thiophen-4-ylidene)malononitrile has been designed and synthesized for high performance solar cells. Abstract : A new non-fullerene acceptor, namely Y10, based on dithienothiophen[3, 2- b ]-pyrrolobenzothiadiazole (TPBT) as the central core and 2-(6-oxo-5, 6-dihydro-4 H -cyclopenta[ c ]thiophen-4-ylidene)malononitrile (TC) as the electron-deficient end group, has been designed and synthesized. Y10 reveals a narrow optical energy gap ( E optg) of 1.35 eV with a broad absorption band from 600 to 900 nm. A wide bandgap polymer, J11, as the donor material ( E optg = 1.96 eV) is used to blend with Y10 for the construction of organic solar cell devices, which achieve an impressive power conversion efficiency (PCE) of 13.46% with an open circuit voltage ( V oc ) of 0.89 V, a short circuit current ( J sc ) of 21.21 mA cm −2, and a fill factor (FF) of 71.55%, with thermal annealing treatment at 100 °C for 5 min and 0.8 wt% 1-chloronaphthalene (CN) as an additive. These results indicate that the incorporation of the TPBT unit as the central core and the TC unit as the electron-deficient end group provides an efficient strategy for the construction of high performance solar cells.